2006 doe hydrogen program revie · 2020. 11. 21. · 6 task 1.1 (production): photoelectrochemical...

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2006 DOE Hydrogen Program Review2006 DOE Hydrogen Program ReviewProduction, Fuel Cell, and Delivery Research

University of South FloridaPresenters: Yogi Goswami and Elias Stefanakos

May 18, 2006

Project ID # PDP37

This presentation does not contain any proprietary or confidential information

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Hydrogen Production (STP37)• Photoelectrochemical/Photocatalytic (USF)• Thermochemical Cycle (UF) • Biomass Gassification(UF)• Solid State Ionic Conductors(USF)

Hydrogen Storage (STP43)• Advanced material-based technologies for on-board

vehicular storage (USF and UF)• Nano-structured Materials (USF)• Nano-structured Films (USF)

Fuel Cells (STP37)• PEM Fuel Cell Research (UCF)• PEM Fuel Cell Research (UF)• PEM Fuel Cell Research (USF)

Delivery (STP37)• Geologic Storage (USF)• Thermal Hydrogen Compressor (USF)

ParticipantsParticipants ProjectsProjectsUniversity of South Florida• CO-PI’s: Yogi Goswami, Elias Stefanakos• V. Bhethanabotla (ChE),, M. Calves (COT), C.

Ferekides (EE), Y. Goswammi (ChE), N. Kislov (CERC), B. Krakow (CERC), , Ashok Kumar (ME), L. Langebrake (COT), D. Morel (EE), G. Moore (CERC), S. Onishi (COT), M. Ross (Civil E), M. Smith (CERC), S. Srinivasan (CERC), E. Stefanakos (EE), P. Wiley (EE), J. Wolan (ChE), 8 graduate students, 2 undergraduate.

University of Florida• L. McElwee-White (Chemistry), B. Lear (ME), M. Su

Lee (ME), S. Ingley (ME), Nikhil Kothurkar (ME), 6 graduate students

University of Central Florida• Clovis Linkous (FSEC)

Participants and ProjectsParticipants and Projects

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OverviewOverviewTimeline• Oct 2004 to Sept 2008• 40% CompleteBudget• Total project funding

– DOE $4.8M ($1.2M/year)– Contractor $1.25M– FY05 $2.9M

Barriers (continued)Task 2: Hydrogen Storage• 2.1: Advanced material-based technologies for on-

board vehicular storage– 3.3.4.2 A-D, J, P, Q (System weight and volume, System

cost, Efficiency, Durability/Operability, Thermal management, Lack of understanding of H2 physisorptionand chemisorption, Reproducibility of performance)

• 2.2: Nano-structured Materials– 3.3.4.2 A-C, J, P, Q (System weight and volume, Efficiency,

Durability/Operability, Thermal management, Lack of understanding of H2 physisorption and chemisorption, Reproducibility of performance)

• 2.3: Nano-structured Films– 3.3.4.2.1 B, D (System cost, Durability/Operability)

Task 3: Fuel Cells• 3.1.1: PEM Fuel Cell Research (UCF)

– 3.4.4.2 A-D (Durability, Cost, Electrode performance; Thermal, Air, and water management)

• 3.2.2: PEM Fuel Cell Research (UF)– 3.4.4.2 A-D, J (Durability, Cost, Electrode performance ;

Thermal, Air, and water management; Start-up time/Transient operation)

• 3.3.2: PEM Fuel Cell Research (USF)– 3.4.4.2 B, C, D, I (Cost, Electrode performance ; Thermal,

Air, and water management; H2 purity/CO Clean-up)Task 4: Delivery• 4.1: Geologic Storage

– 3.2.4.2 G (Feasibility of geologic storage)• 4.2: Thermal Hydrogen Compressor

– 3.2.4.2 B (Reliability and costs of H2 compression)

BarriersTask 1: Hydrogen Production•1.1: Photoelectrochemical/Photocatalytic

–3.1.4.2.6 AP, AQ (Materials efficiency, Materials durability)•1.2: Thermochemical Cycle

–3.1.4.2.7 AU (High temperature thermochemical technology development)

•1.3: Biomass Gassification–3.1.4.2.4 W, 3.1.4.2.4 V (Feedstock cost and availability, Capital cost and efficiency of biomass gasification/pyrolysistechnology)

•1.4: Solid State Ionic Conductors–3.1.4.2.2 H, I, K (Fuel processor capital costs, System efficiency, Grid electricity emmissions, Electricity costs)

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Task 1.1 (production): Task 1.1 (production): PhotoelectrochemicalPhotoelectrochemicalD. L. Morel, C. S. Ferekides, S. D. L. Morel, C. S. Ferekides, S. VakkalankaVakkalanka, S. Bates, S. Bates

Overall To produce H in the $ 0.70 – 2.00/kg rangePhotocatalyst efficiency(sunlight to hydrogen) 14%Photocatalyst cost($/m2) 70Membrane cost($/m2) 50

2004 Develop design parameters for CdSe/Si tandem devicesBegin fabrication of Si devicesInitiate deposition of CdSe on Si

2005 Demonstrate working TO/Si devices with Voc > 500 mVDevelop doped ZnSe p-contactsDemonstrate operable CdSe/Si tandem devices

ObjectivesObjectives

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Task 1.1 (production): Task 1.1 (production): PhotoelectrochemicalPhotoelectrochemical

ApproachApproach

• Construct tandem solar cells with Si(CIGS) and CdSe– Multi-crystalline Si will be phase I, since it is proven technology, but may be too

costly to meet the ultimate cost needed– CIGS is expected to offer a lower cost alternative for phase II– DOE Barrier: Materials Durability

• Band gaps are ideal at 1.1 and 1.7 eV• Si and CIGS efficiencies are a given• The key challenge is to achieve 15% efficiency with CdSe

– DOE Barrier: Materials efficiency

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ResultsResults

Device Fabrication•Si is 0.1 Ω-cm 100 n-type•SnO2 is deposited by MOCVDResults•The objective of 500 mV has been met•Annealing(400C for 30 min.) significantly improves Voc but distorts the curve shape

-0.015

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-0.005

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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Volts

Cur

rent

(Am

ps)

Annealed

As made

SnO2/Si Device PerformanceSnO2/Si Device Performance

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1500 2000 2500 3000 3500

ZnTe Thickness(A)

Atom

ic P

erce

nt

ZnSeTe

(S )

P P –– Contact developmentContact development

• ZnSexTe1-x from MBE growth has exhibited good p-contact properties

• Using cost compatible deposition technologies creates difficulties for controlling stoichiometry requirements for effective doping

• We have discovered regimes in deposition space that result in Zn/Group IV ≅ 1. Initial conductivities are of order 109 Ω-cm.

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Tandem DevicesTandem Devices

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CdSe on TO/Si

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m V

mA

•Operable Tandem devices have been fabricated

•Typical IV performance has been achieved for top CdSe devices

•CdSe QE is currently limited by the SnO2 properties on Si

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Future Work and SummaryFuture Work and SummaryFuture Work• Primary effort will be on further development of the p-contact. This is critical to

generation of sufficiently high Voc’s to dissociate water. While ZnSexTe1-x shows great promise when grown under ideal conditions, those properties may not be attainable with cost-effective growth technologies. If not, we have other options to pursue for the p-contact.

• Further work is needed on improving Si device performance, and particularly with respect to the SnO2 contact. A key issue is developing this contact so that it optimizes Si performance while also serving as an effective growth surface and n-contact for the CdSe device.

Summary• Primary near-term technical objectives have been met

–Voc > 500 mV in Si devices–Operable tandem devices

• Key technical issue for current effort–Improved doping in CdSe p-contacts–Higher Voc’s in CdSe devices

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Task 1.1 (production): Task 1.1 (production): PhotocatalyticPhotocatalyticNikolai Kislov, M. Schmidt, S. Srinivasan, E. Stefanakos, M. SmiNikolai Kislov, M. Schmidt, S. Srinivasan, E. Stefanakos, M. Smithth

Objectives• Develop doped or alloyed TiO2 thin films with improved performance to demonstrate

splitting of H2O between 1.23 and 1.48 VApproaches•Extending light absorption into visible ragion by coupling of TiO2 with a small

bandgap semiconductor (ZnFe2O4, Fe2O3, or WO3)•TiO 2 bandgap reduction by carbon doping•Preparation of photocatalytic films and nanoparticles using inexpensive spray

pyrolysis depositionExperimental techniques• Improvement of the accuracy of the photocatalytic phenol degradation analysis

by using multicomponent approach•Design of the reactor for visible light photolysis•Preparing nanosized powders by High Energy Ball Milling •Optical characterization of nanopowders (Kubelka-Munk theory) •ZnFe2O4 characterization using optical, XRD, SEM, and AFM analysis

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Task 1.1 (production): Task 1.1 (production): PhotocatalyticPhotocatalytic

AccomplishmentsAccomplishments --TiOTiO22--ZnFeZnFe22OO44 NanocompositesNanocomposites

Phenol Degradation by TiO2 (Aldrich) Photocatalyst

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Wavelength, nm

Abs

orba

nce

0 min 15 min 30 min 45 min60 min 75 min 90 min 105 min120 min 150 min 180 min

• Organic (phenol) degradation is used to estimate photocatalyst’s redox reactions efficiency.• A multicomponent approach in optical spectra analysis has been proposed for the result interpretation• Expected Intermediate Products of Phenol Degradation (Catechol, Hydroquonine, p-Benzoquonine, o-

Benzoquonine, Muconic acid, Dibenzofuran, Resorcicol, Oxalic acid)

Sesha S. Srinivasan, Nikolai Kislov, Jeremy Wade, Matthew T. Smith, Elias K. Stefanakos, Yogi Goswami, “Mechanochemical synthesis, structural characterization and visible light photocatalysis of TiO2/ZnFe2O4nanocomposites,” Accepted by MRS Proceedings, 2006

C(λ) = Σak.φk(λ)

Kinetics of Phenol Degradation by TiO2 (Aldrich) Photocatalysis

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Time (min)

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cent

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n (p

pm) Phenol Catechol Hydroquonine p-Benzoquonine

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Task 1.1 (production): Task 1.1 (production): PhotocatalyticPhotocatalyticAccomplishments Accomplishments -- TiOTiO22--ZnFeZnFe22OO44 NanocompositesNanocomposites

• TiO2-ZnFe2O4 nanocomposites were optimized based on control parameters such ball to powder weight ratio, milling duration, milling speed, and calcination temperature.

• Particularly, the nanocomposite having 5 at.% ZnFe2O4 and ball-milled for 10 hours is more than twice efficient in comparison with pure TiO2 photocatalyst.

y = 0.0002xR2 = 0.9958

y = 0.0005xR2 = 0.8876

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-ln(C

/Co)

5 at.% ZnFe2O4- TiO2 Aldrich 10 h BM TiO2 Aldrich

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4

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6

1.5 2 2.5 3 3.5 4Energy, eV

(F(R

')*h ¬

)1/2

TiO2 Aldrich

TiO2 Aldrich + 5 at.% ZnFe2O4,10 h ball-mill, 400 C 3h

E=3.3 eV

E=3.24 eV

Red shift in optical absorption because of doping by ZnFe2O4

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Accomplishments Accomplishments -- TiOTiO22--ZnFeZnFe22OO44 NanocompositesNanocompositesA detailed investigation of quantum-sized effects in ball-milled ZnFe2O4has been performed in order to understand the photophysical properties of ZnFe2O4/TiO2 nanoclusters

XRD Analysis was used for particle size estimation

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Milling time (hours)

Part

icle

siz

e (n

m)

2.2

2.3

2.4

2.5

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Cluster Size (nm)

Ener

gy G

ap (e

V)

The dependence of the optical bandgapof ZnFe2O4 on the cluster size

The dependence of the particle size of ZnFe2O4 on the milling time

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0

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Energy, eV

(F(R

')*h π

)1/2

TiO2 Degussa

TiO2 Deg 600C hex 17h BM600C N2 450C air


Accomplishments Accomplishments -- Carbon doping of TiOCarbon doping of TiO22

Developed TiO2 carbon doped photocatalyst having improved photocatalytic properties

Particularly, the carbon doped TiO2 photocatalyst is two times more efficient than pure TiO2 photocatalyst

E=3.35 eV

E=3.1 eV

Red shift in optical absorption because of doping by carbon

y = 0.002089x - 0.032648R2 = 0.994599

y = 0.0009x + 0.1337R2 = 0.9173

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-ln(C

/C0)

TiO2 Degussa modified by carbon doping TiO2 Degussa

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Project SummaryProject SummaryRelevance:

Provided fundamental and experimental basis for development of efficient electrode materials for use in hydrogen production photochemical cell.

Approach:Extending light absorption into visible region by coupling of TiO2 with a small bandgap semiconductor (ZnFe2O4, Fe2O3, or WO3)TiO 2 bandgap reduction by carbon dopingPreparation of photocatalytic films and nanoparticles using inexpensive spray pyrolysis deposition

Technical Accomplishments and Progress:Demonstrated TiO2 photocatalysts having improved photocatalytic activity in organic degradation experiments

Proposed Future Research:Complete experimental transformation from organic degradant to H2 production using visible light photocatalysis.Design/construct apparatus and begin photocatalytic experimentsDevelop doped TiO2 films having improved photocatalytic activity for water splitting experiments

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Task 1.1 (production): Task 1.1 (production): Photoelectrochemical/PhotocatalyticPhotoelectrochemical/Photocatalytic

PublicationsPublications• Sesha S. Srinivasan, Nikolai Kislov, Jeremy Wade, Matthew T. Smith, Elias K. Stefanakos,

Yogi Goswami, “Mechanochemical synthesis, structural characterization and visible light photocatalysis of TiO2/ZnFe2O4 nanocomposites,” Accepted by MRS Proceedings, 2006

• P. Mahawala, S. Vakkalanka, S. Jeedigunta, C. S. Ferekides and D. L. Morel, “Transparent Contact Development for CdSe Top Cells in High Efficiency Tandem Structures”, Proceedings of the 31st IEEE PVSC, Orlando, 2005.

• “Transparent high-performance CDSE thin-film solar cells”,Thin Solid Films, Volumes 480-481, 1 June 2005, Pages 466-470 P. Mahawela, S. Jeedigunta, S. Vakkalanka, C.S. Ferekides and D.L. Morel

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Task 1.2 (production): Task 1.2 (production): ThermochemicalThermochemicalM. Su Lee, S. Dolan, H. Ingley M. Su Lee, S. Dolan, H. Ingley –– University of FloridaUniversity of FloridaY. Goswami, E. Stefanakos Y. Goswami, E. Stefanakos –– Univ. of South FloridaUniv. of South FloridaObjectives• Investigate UT-3 Thermochemical cycle and conduct kinetic studies• Lower H2 production cost by increasing H2 yield with an improved

pellet formulation• Reduce operating cost by lowering the reactor operating temperature

Approach• Evaluation of characteristics of Ca-pellets and Fe-Pellets to improve

their formulation • Chemical kinetic studies to evaluate and improve the pellet cyclic life,

reaction rates and conversion using lab-scale apparatus• Feasibility experiments

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Task 1.2 (production): Task 1.2 (production): ThermochemicalThermochemical

Procedure to Make a CaProcedure to Make a Ca--pelletpellet

Chemistry of Metal Alkoxide

A PresinteredPellet

Sieved Powder

Drying and Mixing with Additives

Die pressing

A Porous Ca-Pellet supported by CaTiO3

Sintering

Remove Additives

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Accomplishments Accomplishments -- Experimental SetExperimental Set--up and up and ThermogravimetricThermogravimetric BalanceBalance

Thermogravimetric Balance

Experimental Set-up

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Accomplishments Accomplishments -- Pore Size Distributions of CaPore Size Distributions of Ca--pellets by Additivespellets by Additives

• Macropores contribute to diffusion characteristic inside the pellet.• The addition of corn starch and stearic acid increases macropores greater than 5μm with a slight

decline in strength while the addition of graphite decrease the strength steeply.

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AccomplishmentsAccomplishments -- Conversion Profiles of ReactionsConversion Profiles of Reactions

Bromination Hydrolysis

Bromination Hydrolysis

Unreacted pellet After hydrolysis

After bromination

Unreactedpellet

After hydrolysis

After bromination

• Initial trend of conversion profiles was in relatively good agreement with the results reported by M. Sakurai et al, 1995[1]

• Degradation and low hydrolysis rate were observed during the cyclic operations.

• Half of pore volume was reduced by increasing the volume of solid reactant in the process of bromination.

• Most of pores greater than 5μm were regenerated after hydrolysis while pores less than 5μm weren’t. This showed that the reduction lead to degradation.

1) M. Sakurai, A. Tsutsumi and K. Yoshida, 1995, “Improvement of Ca-Pellet Reactivity in UT-3 Thermochemical Hydrogen Production Cycle.” Int. J. Hydrogen Energy, Vol. 20, pp.297-301.

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SummarySummary• Objective : Investigate various aspects of the UT-3 cycle in order to improve the process

performance.

• Approach : Understand the reaction kinetics, solid reactant behavior and process thermodynamics

• Technical Accomplishments and Progress- Completed installation of laboratory scale facility- The bromination and hydrolysis of Ca-pellet has been conducted using laboratory experimental

set-up.- Degradation and low hydrolysis rate was observed.- The pore size distribution data showed that the reduction of pore volume is a cause of

degradation and low hydrolysis rate

• Proposed future research- Understand the mechanism of degradation and speed up the hydrolysis process - Develop a pelletization process for Fe-pellets- Study kinetics of Fe-pellets- Thermodynamic analysis of the cycle

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PublicationsPublications• Man Su Lee, Yogi Goswami, Ben Hettinger, and Sanjay Vijayaraghavan, “Development of

Calcium Oxide Pellets for UT-3 Thermochemical Cycle”, Abstract accepted for 2006 ASME International Mechanical Engineering Congress and Exposition.

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Task 1.3 (production): Biomass GasificationTask 1.3 (production): Biomass GasificationM. Mahishi, M. Nath, N. Rajvanshi, W. Lear M. Mahishi, M. Nath, N. Rajvanshi, W. Lear –– Univ. of FloridaUniv. of FloridaY. Goswami, E. Stefanakos Y. Goswami, E. Stefanakos –– Univ. of South FloridaUniv. of South Florida

Overall • Improve H2 yield and process efficiency (heat integration and alternate gas clean-up approaches)• Reduce capital cost by combining process (gasification, reforming and shift) steps and operations•Improve gasification efficiency by developing a model-based controller for a biomass gasifier

2005 •Conduct theoretical studies of sorbent enhanced biomass gasification•Develop experimental set-up•Modeling of gasifier

– develop dynamic math model of a biomass gasifier– study the time dependence of reformate properties on

biomass composition & steam to biomass ratio2006 • Experimentally determine effect of sorbent addition on H2 (& CO, CO2) yields

•Conduct energy analysis of biomass gasification•Simulate in MATLAB/SIMULINK & design a model-based controller to

– take corrective action on system abnormalities – ensure uniform H2 output

Objectives

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Task 1.3 (production): Biomass Gasification Task 1.3 (production): Biomass Gasification

Approach (Thermodynamics)Approach (Thermodynamics)• Task 1: Thermodynamic studies (complete)

― Determine process conditions for maximum thermodynamic H2 yield― Develop ASPEN models for conventional & sorbent based biomass gasification

• Task 2: Experimental studies (50% complete)― Fabricate test set-up― Conduct tests with and without sorbent to find H2, CO & CO2 yields

• Task 3: Energy analysis (10% complete)― Study energy consumption of conventional & sorbent enhanced gasification― Identify energy efficient methods for regenerating spent sorbent

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Task 1.3 (production): Biomass GasificationTask 1.3 (production): Biomass Gasification

Approach (Optimization)Approach (Optimization)Task 1: Modeling

• Develop a physics-based thermodynamic model for discrete reformer elements. • Transform the PDE into a set of ODEs in time.• Linearize the model for development of a suitable controller.

Task 2: Simulation• Solve ODEs in Matlab for

- transient temperature distribution in reformer- reformate concentration as a function of time

Task 3: Model Validation• Match the simulated results with experimental results• Validate the model

Task 4: Controller Design• Design controller to reject the following disturbances into the system:

– biomass inconsistencies– biomass flow rate– catalyst degradation– tar formation

• Design an ideal model-based control scheme. • Implement the controller and evaluate the change in performance of the gasifier in terms on H2 yield.

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Accomplishments (Thermodynamics)Accomplishments (Thermodynamics)Experimental result: Product gas composition of pine mulch steamgasified at 600oC with and without CaO sorbent

Gas composition with & without sorbent

0102030405060708090

H2 CH4 CO CO2 C2H6 otherGas

vol %

Without CaO With CaO

• H2 yield increased by 20%; CO and CO2 in product gas reduced by 44% and 60.6% respectively from base (no sorbent) case

• higher gas yield (about 30%) observed in presence of sorbent

• product gas has less tars and particulates while using sorbent

• higher H2 yield obtained at lower temperature offers potential to reduce gasification temperature (by about 100-150oC)

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Task 1.3 (production): Biomass Gasification Task 1.3 (production): Biomass Gasification

Future WorkFuture WorkFY 2006 (Thermodynamics)

Quarter 3:• Conduct further experiments to determine gas yield (mainly H2, CO, CO2 yields) at different

temperatures with and without sorbentQuarter 4:

• Conduct an energy analysis of biomass steam gasification considering heat losses and equipment inefficiencies

FY 2006 (Optimization)• Model validation by comparing with experimental results

• Design a few controllers to maintain optimal operating conditions of the reformer.

• Compare the results and propose the ideal controller

FY 2007 (Thermodynamics)• Identify methods of regenerating spent sorbent using waste heat from other applications

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PublicationsPublications• “Hydrogen production from ethanol: A thermodynamic analysis of a novel sorbent enhanced

gasification process”, Mahishi M.R., Sadrameli, S. M., Vijayaraghavan S., Goswami D. Y., American Society of Mechanical Engineers, Advanced Energy Systems Division (publication) AES vol 45, pp 455-463, 2005

• “A Novel Approach to Enhance the Hydrogen Yield of Biomass Gasification Using CO2Sorbent”, Mahishi M.R., Sadrameli, S. M., Vijayaraghavan S., Goswami D. Y. under review with ASME Journal of Engineering for Gas Turbines and Power

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Objective• Economic electrolytic hydrogen production through better electrolytes and electrochemical cellsApproach• Scavenging the anode with a reducing agent. This agent may be landfill gas (or other biogas),

synthesis gas or industrial waste products.• An optimum choice of temperature can provide a good balance of efficiency and low cost . The

temperature should be above 150 ºC (to lower the electricity demand) and below 300 ºC (where a quantum jump occurs in cost and difficulty of system construction and operation).

• An electrolyzer with a scavenged anode is effectively a gas shift reactor in which electrolysis replaces shift, separation and purification with one step. This mitigates the need for economies of scale and addresses the most difficult barriers for both gas shift and electrolytic hydrogen production.

• To implement the stated solutions we are developing electrochemical cells with electrolytes that have the following characteristics:

– True solid state proton conductors– Operate between 100 and 300 ºC– No liquid water required and no water loss at elevated operating temperature– Reduced catalyst requirements– Impermeable to fuels, scavengers, reaction intermediates, molecular products and catalysts

Task 1.4 (production): Solid State Task 1.4 (production): Solid State Ionic Conductor DevelopmentIonic Conductor DevelopmentB. Krakow, P. Wiley, L. EcklundB. Krakow, P. Wiley, L. Ecklund--Mitchell, D. Payne, E. Weaver , E. StefanakosMitchell, D. Payne, E. Weaver , E. Stefanakos

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Task 1.4 (production): Solid State Ionic Conductor DevelopmentTask 1.4 (production): Solid State Ionic Conductor Development

Permeability ResultsPermeability Results• CsHSO4 pellets impermeable to

methanol were manufactured• Permeability was only exhibited in

the first hour of experiment, the stopped

• Impermeability due to methanol appears to be a combination of heating effect, and interaction to methanol itself

• Pellets rendered impermeable to methanol continued to be so several days later

• Initial permeability dropped by an order of magnitude for reused pellets

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Synthesis and Material CharacterizationSynthesis and Material CharacterizationHigh purity CsHSO4 was synthesized by reacting Cs2SO4 with sulfuric acid, then crystallizing out of solution with an organic (methanol). Quality of CsHSO4was confirmed with the following characterization methods:•Combined TGA and DSC-distinct transition at 141 ºC to high temperature phase at 22.1 J/g, chemical decomposition in air at 163 ºC to melting at 196 ºC•XPS with Mg source-distinct crystalline peaks, Cs to S ratio of 1:1 on surface, some oxide formation on surface•XRD-Crystalline peaks, strong match to known CsHSO4 in 2Θ = 10-75º range

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Future Work and SummaryFuture Work and SummaryFuture Work• Performance and stability• Studies of electrolytes and cells will continue. New electrolyte materials will be sought and

investigated for use with specific scavengers.• We will apply metallurgical and semiconductor processing techniques to inorganic solid

electrolyte materials to try to prepare strong and sturdy thin electrolytes.• A monitoring and control system will be acquired and installed.• Electrode attachment techniques to minimize contact resistance will be pursued. • Catalysts and surface treatments will be applied to attempt to increase power densities.• We will continue to test permeability of solid electrolytes to feedstocks and scavengers.Summary• Impermeability of pellets after high temperature treatment with methanol while maintaining

other crucial characteristics (conductivity, strength) supports viability of CsHSO4 as material in combined hydrogen production/separation processes.

• CsHSO4 produced in current synthesis is high-purity, with sharp crystalline structure, and reproducible thermal properties.

• Groundwork has been laid to begin rigorous testing of performance of electrodes and catalysts to specific fuel gases

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Task 3.1.1 (Fuel Cells): PEM Fuel Cell ResearchTask 3.1.1 (Fuel Cells): PEM Fuel Cell ResearchC. Linkous C. Linkous –– Univ. of Central FloridaUniv. of Central FloridaObjectives• Lower the cost of fuel cell-generated electricity by decreasing the cost per unit

power for PEM electrolytes• Improve long-term chemical stability of PEM electrolytes operating at ≤ 120 oC• Maintain or improve high proton conductivity of PEM electrolytes• Minimize water content necessary to support high proton conductivityApproach• Heavily sulfonate polymers to promote proton conductivity, but cross-link to

prevent solubility and mechanical stability problems• Use only as much fluorine in the polymer as is necessary to promote conductivity

and chemical stability- place fluorines near the sulfonic acid groups to increase acidity- surface fluorinate to provide protection where hydroxyl radicals are

generated• Develop accelerated test apparatus to evaluate prototype PEM’s

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Task 3.1.1 (Fuel Cells): PEM Fuel Cell Research (UCF)Task 3.1.1 (Fuel Cells): PEM Fuel Cell Research (UCF)

AccomplishmentsAccomplishments• Demonstrated protection of amine substituents on

benzyltrifluoride monomer by making the acetamide, a necessary step in the synthesis of fluorosulfonic PEEK polymer

• Developed mechanical, permeation, and conductivity methods for accelerated testing of PEM electrolytes under oxidizing conditions

• Synthesized highly conductive SPEEK (260 EW) to incorporate into cross-linked PEM electrolytes

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AccomplishmentsAccomplishments

Accelerated testing for peroxide stability on a fuel cell electrolyte

Neosepta® solid polymer electrolyte exposed to 3.5% H2O2 solution at 50 oC. (100x magnification)

Day 1 Day 3 Day 11

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H2O2

H2O

H2O


AccomplishmentsAccomplishmentsPermeability tests on 0.025mm polystyrene at 10 psi and 80 oC

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Future WorkFuture Work• Remainder of FY06

- prepare fluorosulfonic acid versions of S-PEEK and other engineering polymers- determine limits of cross-linking, degree of sulfonation, and proton conductivity - finalize accelerated PEM test method- measure durability of surface-fluorinated PEM’s

• FY07- combine cross-linking and partial fluorination strategies into new PEM membranes- test prototype PEM’s in fuel cell configuration

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Task 3.1.2 (Fuel Cells): PEM Fuel Cell Research (UF)Task 3.1.2 (Fuel Cells): PEM Fuel Cell Research (UF)N. Kothurkar, Y. Goswami, E. StefanakosN. Kothurkar, Y. Goswami, E. Stefanakos

Overall • Develop cheaper PEM material alternatives to Nafion®•High Temperature, Low humidity operation

•Low fuel crossover

• Experimental setup for wide temperature range testing

2005 •Set up experimental test bed •Synthesize polymer (ABPBI) for low humidity, high temperature operation

2006 • Fabricate MEA•Test Performance of ABPBI at high temperature•Test Performance of ABPBI at sub-freezing temperature

Objectives

39

Task 3.1.2 (Fuel Cells): PEM Fuel Cell Research (UF)Task 3.1.2 (Fuel Cells): PEM Fuel Cell Research (UF)

ApproachApproachSetup fuel cell test stand• Construct test stand with temperature, humidity, etc. control• Modify for low temperature operation for freeze testing

PEM Material Development• Synthesize ABPBI—poly(2, 5-benzimidazole) • Fabricate membrane electrode assemblies (MEA)• Test MEAs under different temperature regimes

40


Accomplishments (Test setAccomplishments (Test set--up)up)

0.40.50.60.70.80.9

11.1

0 200 400 600 800Current Density (mA/cm^2)

Volta

ge (V

)

Test1Test2Test3Test4

0.40

2.40

4.40

6.40

8.40

10.40

0 200 400 600 800Current Density (mA/cm^2)

Pow

er (W

)

Test1Test2Test3Test4

Single cell

Back pressure valves

RH Probe

Resistance Load

Current transducer

Mass Flow Cont.

Humidifier

Control Panel

Repeatability Testing, Nafion® MEA

Test Bed

41


Accomplishments Accomplishments –– Synthesis and Synthesis and Characterization of Poly(2,5Characterization of Poly(2,5--benzimidazole)benzimidazole)

EDX-Elemental Analysis

SEM BSE Intrinsic Viscosity- MW

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5Concentration gm/dL

Inhe

rent

Vis

cosi

ty

Intrinsic Viscosity = 1.78 g/dLMW = 14,600

42


Future Work Future Work FY 2006

Quarter 3:• Increase molecular weight of ABPBI• Develop catalyst formulation• Fabricate MEA

Quarter 4:• Evaluate performance of ABPBI at high temperatures (120-180°C)• Evaluate performance of ABPBI at sub-freezing temperatures.

FY 2007• Evaluate and reduce phosphoric acid leaching

43

Task 3.1.3 (Fuel Cells): PEM Fuel Cell Research (USF)Task 3.1.3 (Fuel Cells): PEM Fuel Cell Research (USF)J. Wolan, B. Grayson, E. Stefanakos, V. GuptaJ. Wolan, B. Grayson, E. Stefanakos, V. GuptaObjectives• Develop alternative anodic catalyst systems; increasing activity,

reducing Pt loading and preventing CO poisoning through novel uses of alloying gold nano-particle/TiO2 systems.– Additional improvements in anode tolerance to carbon monoxide are required

to facilitate simplification of the system and to reduce cost and weight [1]• Increase the operating temperature of polymer-based proton

exchange fuel cells through the incorporation of nano-composite membrane additives; increasing catalyst activity and improving fuel cell efficiencies.– The proposed membrane material must meet the conductivity requirements

over a range of operating conditions from -20°C to 120°C [2]• 0.10 S/cm proton conductivity at Operating Temp• 0.07 S/cm proton conductivity at Room Temp

1. DOE, Multi-Year Research, Development and Demonstration Plan, pg 3-762. Draft Funding Opportunity Announcement Research and Development of Polymer Electrolyte Membrane (PEM)

Fuel Cells for the Hydrogen Economy, 4/25/05

44

Task 3.1.3 (Fuel Cells): PEM Fuel Cell Research (USF)Task 3.1.3 (Fuel Cells): PEM Fuel Cell Research (USF)

ApproachApproach• Custom anodic catalysts consisting of platinum,

ruthenium, and gold nanoparticles have been developed.

• Stabilized gold nanoparticles supported on TiO2selectively oxidize CO below 100oC

• β-zeolite nanoparticles have been incorporated with functionalized cast NafionTM films; increasing operating temperatures while maintaining sufficient water retention.

45


Gold Nanoparticles Preparation*Gold Nanoparticles Preparation*

• Two Phase Transfer Method– Results in gold particles <10 nm– TOABr = Stabilizing Agent

tetra-octyl-ammonium-bromide Water

HAuCl4

Toluene

TOABr

NaBH4

Au

Au

Au

Au

46


Catalyst ResultsCatalyst Results

• FTIR analysis comparing Pt/Ru/TiO2 with Pt/Ru/Au/TiO2 catalysts as shown in Fig. 1 shows improved CO oxidation of 3% at operation temps of 80-120oC.

• SEM images imply gold nanoparticles sizes less than 100 nm (Figure 2).

• XRD spectrum →TiO2 to be anatase; a partial phase change to rutile occurs when exposed to temps. approaching 500-550oC which proves to be beneficial (Figure 3)

• XPS analysis is underway to determine the most active oxidation state of the gold catalyst species.

Figure #1

Figure #3

Figure #2

100nm100nm

TiO2sphere

Gold Nanoparticles

Pt/Ru/Au/TiO2

Pt/Ru/TiO2

Anatase

Rutile

47


ββ--zeolite membrane creation for high zeolite membrane creation for high temperature PEMtemperature PEM• β-zeolites were fully incorporated into

cast NafionTM films. Chosen due to their pore size, structure, acid stability, water retention, and increased proton conduction.

• Increased proton conductivity is achieved by functionalizing the films with phosphotungstic acid.

• XPS analysis of the zeolite crystals revealed no change in composition during particle reduction process

Ball milled β-zeolite β-zeolite crystalline structure

Fully cast nanocomposite film

Fully cast nanocomposite film

48


Future Work and SummaryFuture Work and SummaryFuture Work• Optimize gold catalyst preparation techniques and increasing selectivity towards

the production of CO2 over H2O formation• Determine humidity effects on catalyst operation• Further characterization of β-zeolites using XRD, TGA, and proton conductivity

measurements• Fully develop nanocomposite membranes capable of incorporation into a 25cm2

membrane electrode assembly (MEA)• Incorporate new MEA into a hydrogen fuel cell, operate at elevated temperatures

and evaluate efficiency and performance.Summary• Pt/Ru/Au/TiO2 nano-catalyst shows approx. 3% improvement over conventional

catalyst in selective oxidation of CO in operation temperature ranges of 80-120oC. • β-zeolite nanocomposite acid functionalized membranes have been successfully

developed for incorporation into a high temperature proton exchange fuel cell MEA.

49

Task 4.1 (delivery) Geologic HTask 4.1 (delivery) Geologic H22 StorageStorageKim Clayback, Mark Ross, G. Moore, E. StefanakosKim Clayback, Mark Ross, G. Moore, E. Stefanakos

Objectives• Identify and rank potential sites• Define criteria and storage requirements

for reservoirs• Select an appropriate numerical model

for reservoir performance• Simulate full scale reservoir economics

and operations

50

Task 4.1 (delivery) Geologic HTask 4.1 (delivery) Geologic H22 Storage Storage

Accomplishments: Established Accomplishments: Established criteria for reservoircriteria for reservoir

Formation TypeCaverns Aquifers Depleted Reservoirs

Depth 455 - 915 m 300 - 760 m 150 - 1820 m

Pressure 6.9 - 13.7 e3 kPa 6.9 - 13.7 e3 kPa 3.4 - 17.2 e3 kPa

Capacity 0.6-3.0 e6 Nm3 3.0 e6 - 6.0 e8 Nm3 3.0 e6 - 6.0 e8 Nm3

Porosity n/a .25-.40 .15-.30

Prioritized and identified a suitable geologic feature to simulate a hydrogen gas storage model in a solution mined cavern.

51

Task 4.1 (delivery) Geologic HTask 4.1 (delivery) Geologic H22 StorageStorage

Accomplishments: Established Accomplishments: Established Formation Benefits and DrawbacksFormation Benefits and DrawbacksBenefits• Depleted Reservoirs

― Geologic characteristics generally well known

― Transportation infrastructure in place

• Aquifers― Geographically well dispersed― Large volumetric storage

possibilities• Salt Caverns

― Easiest, quickest recovery of gas― Lowest cushion gas requirement

Drawbacks• Depleted Reservoirs

― Possible chemical reactions with petroleum products

― Not located near population (end user) centers

• Aquifers― Expensive exploration of geologic

properties― Greatest cushion gas requirement― Additional cost of dehydration of gas

during recovery process― Additional installation expense for

wells at the perimeter for recovery • Salt Caverns

― Generally the smallest formation for storage use

― Limited geographic distribution

52

Task 4.1 (delivery) Geologic HTask 4.1 (delivery) Geologic H22 StorageStorage

Future WorkFuture Work

• Simulation of a brine compensated cavern model.

• Simulation of porous media reservoir with a numerical model.

• Engineering cost analysis of operational system.

53

Task 4.2 (delivery): Advanced Thermal HTask 4.2 (delivery): Advanced Thermal H22 CompressorCompressorB. Krakow, S. Srinivasan, P. Wiley, D. Escobar, E. Stefanakos, B. Krakow, S. Srinivasan, P. Wiley, D. Escobar, E. Stefanakos,

Objectives• The objective of this project is

reliable compression of hydrogen to the DOE target pressure of 5,000 - 10,000 psi with no lubricant contamination.

• System Design–Alloy Preparation–Power Supply Characteristics–Alloy Heat Capacity Measurement–Alloy Mass Calculation

• Address barrier 3.2.4.2 B (Reliability and costs of H2compression)

Approach• An advanced hydride thermal compressor will be developed that is

lighter, smaller, cheaper and faster than any built previously. The advanced approach will take advantage of the benefits of high temperatures and very rapid cycling achieved by employing electric discharge heating. It will have no moving parts other than valves (hence low maintenance, long life, reliable, no lubrication or hydrogen contamination by lubricants).

Efficiency benefits• Carnot efficiency is enhanced by higher temperature differentials. • No heat is dissipated by thermal cycling of the coolant. The heat

capacities of the water and cooling tubes are no longer an issuebecause their temperatures are no longer cycling.

Size Reduction• Cycling frequency up to 20 times greater.• About 5 times fewer stages.• Size and alloy requirements reduced by up to (5x20=) 2 orders of

magnitude. Large economic implications.

54

In the 6 months since this task began we have:• Prepared and characterized (XRD and DSC) sample of

ZrMn2 alloy by ball milling and sintering the metal powders.

• Acquired ZrMn2 DSC data with a view to determining its heat capacity (design parameter)– Calculated the required alloy mass– Calculated the required hydrogen mass

• Reactivated a high voltage power supply that was once used for lightning research and has properties needed for producing the electric discharge needed for this project..

Task 4.2 (delivery): Advanced Thermal HTask 4.2 (delivery): Advanced Thermal H22 CompressorCompressorAccomplishmentsAccomplishments

55

Acknowledgements and InteractionsAcknowledgements and Interactions•• Hydrogen Hydrogen Workshop(sWorkshop(s) at USF) at USF

–– Dr. Jim Wang, SNL; Dr. Bill Tumas, LANL; Dr. Lin Simpson, NREL; Dr. Jim Wang, SNL; Dr. Bill Tumas, LANL; Dr. Lin Simpson, NREL; Dr. Craig Jensen, Univ. Hawaii; Dr. Jim Fenton, FSEC; Dr. John Dr. Craig Jensen, Univ. Hawaii; Dr. Jim Fenton, FSEC; Dr. John PetrovicPetrovic, DOE (agreed to visit in June, DOE (agreed to visit in June’’06)06)

•• US Department of Energy (DEUS Department of Energy (DE--FG36FG36--04GO14224)04GO14224)• IFE, Norway; AIST, Japan• University of Hawaii• HY-Energy Inc; SWRI• NREL; NNRC, USF• University of Florida• University of Central Florida (FSEC)• Sigma-Aldrich Fine Chemicals

2006 doe hydrogen program revie · 2020. 11. 21. · 6 task 1.1 (production): photoelectrochemical...

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